/* cubetex.c  key: 1=spin, 2=stop, q=quit  */
/* Rotating cube with texture mapping      */
/* mouse buttons control axis of rotation  */
/* keyboard allows start/stop/quit         */
/* E. Angel, Interactive Computer Graphics */

#include <stdlib.h>
#include <string.h>
#include <GL/glut.h>

static GLfloat vertices[][3] = {
  {-1.0,-1.0,-1.0},{1.0,-1.0,-1.0},
  {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0}, 
  {1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}};
static GLfloat colors[16][4] = {
  {0.0,0.0,0.0,0.5}, {1.0,0.0,0.0,0.5},
  {1.0,1.0,0.0,0.5}, {0.0,1.0,0.0,0.5}, {0.0,0.0,1.0,0.5}, 
  {1.0,0.0,1.0,0.5}, {1.0,1.0,1.0,0.5}, {0.0,1.0,1.0,0.5},
                  /* draw in white to get actual texture color */
  {1.0,1.0,1.0,1.0}, {1.0,1.0,1.0,1.0},
  {1.0,1.0,1.0,1.0}, {1.0,1.0,1.0,1.0}, {1.0,1.0,1.0,1.0}, 
  {1.0,1.0,1.0,1.0}, {1.0,1.0,1.0,1.0}, {1.0,1.0,1.0,1.0}};
static GLfloat theta[] = {0.0,0.0,1.0};
static GLint axis = 2;
static int w = 8; /* zero for multicolor */

static void polygon(int a, int b, int c , int d)
{
  /* draw a polygon via list of vertices */
  glBegin(GL_POLYGON);
    glColor4fv(colors[a+w]);
    glTexCoord2f(0.0,0.0); 
    glVertex3fv(vertices[a]);
    glColor4fv(colors[b+w]);
    glTexCoord2f(0.0,1.0);
    glVertex3fv(vertices[b]);
    glColor4fv(colors[c+w]);
    glTexCoord2f(1.0,1.0); 
    glVertex3fv(vertices[c]);
    glColor4fv(colors[d+w]);
    glTexCoord2f(1.0,0.0); 
    glVertex3fv(vertices[d]);
  glEnd();
}

static void colorcube(void)
{
  /* map vertices to faces */
  polygon(0,3,2,1);
  polygon(2,3,7,6);
  polygon(0,4,7,3);
  polygon(1,2,6,5);
  polygon(4,5,6,7);
  polygon(0,1,5,4);
}

static void display(void)
{
  char msg[] = "type c for cube color, w for white cube, both have colored texture";
  int i, len;
  
  /* display callback, clear frame buffer and z buffer,
     rotate cube and draw, swap buffers */
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();
  glPushMatrix();
    glColor3f(1.0, 0.0, 0.0);
    glRasterPos2f(-1.9, -1.9);
    len = strlen(msg);
    for (i = 0; i<len; i++)
      glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, msg[i]);
  glPopMatrix();
  glRotatef(theta[0], 1.0, 0.0, 0.0);
  glRotatef(theta[1], 0.0, 1.0, 0.0);
  glRotatef(theta[2], 0.0, 0.0, 1.0);
  colorcube();
  glutSwapBuffers();
}

static void spinCube(void)
{
  /* Idle callback, spin cube 1/4 degree about selected axis */
  theta[axis] += 0.25;
  if( theta[axis] > 360.0 ) theta[axis] -= 360.0;
  glutPostRedisplay();
}

static void mouse(int btn, int state, int x, int y)
{
  /* mouse callback, selects an axis about which to rotate */
  if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;
  if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;
  if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;
}

static void myReshape(int w, int h)
{
  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  if (w <= h)
    glOrtho(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,
            2.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);
  else
    glOrtho(-2.0 * (GLfloat) w / (GLfloat) h,
            2.0 * (GLfloat) w / (GLfloat) h, -2.0, 2.0, -10.0, 10.0);
  glMatrixMode(GL_MODELVIEW);
}

static void key(unsigned char k, int x, int y)
{
  if(k == '1') glutIdleFunc(spinCube);
  if(k == '2') glutIdleFunc(NULL);
  if(k == 'c') w = 0;
  if(k == 'w') w = 8;
  if(k == 'q') exit(0);
}

static void init()
{
  GLubyte image[64][64][3];
  int i, j, r, g, b;
  for(i=0;i<64;i++)
  {
    for(j=0;j<64;j++)
    {
      r = ((((i&0x8)==0)^((j&0x8))==0))*255;
      g = 2*(i+j);
      b = 255-2*(i+j);
      image[i][j][0]= (GLubyte)r;
      image[i][j][1]= (GLubyte)g;
      image[i][j][2]= (GLubyte)b;
    }
  }
  glEnable(GL_TEXTURE_2D);
  glTexImage2D(GL_TEXTURE_2D,0,3,64,64,0,GL_RGB,GL_UNSIGNED_BYTE, image);
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); 
  glClearColor(1.0,1.0,1.0,1.0);
}

int main(int argc, char *argv[])
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowSize(500, 500);
  glutCreateWindow("colorcube");
  /* need both double buffering and z buffer */
  glutReshapeFunc(myReshape);
  glutDisplayFunc(display);
  glutIdleFunc(spinCube);
  glutMouseFunc(mouse);
  glutKeyboardFunc(key);
  glEnable(GL_DEPTH_TEST);
  init();
  glutMainLoop();
  return 0;
}